WE ARE EXPLORING SYNTHETIC ROUTES TOWARD THE SYNTHESIS OF AMINO ACIDS WHICH CONTAIN EITHER A SELENIUM OR TELLURIUM ATOM. CURRENT TARGETS ARE TE AND SE LABELED METHIONINE, TRYPTOPHAN, CYSTINE, AND CYSTEINE. ONE OF CURRENT TARGETS IS THE SYNTHESIS OF TELLUROCYSTEINE. THIS DERIVATIVES, WHEN INCORPORATED INTO BIOMACROMOLECULES, CAN ACT AS A RATIONAL HEAVY ATOM DERIVATIVE FOR X-RAY DIFFRACTION STUDIES AND AS NOVEL NMR PROBES. THE STARTING MATERIAL IODOALANINE IS CONVENIENTLY CONSTRUCTED. THE SYNTHESIS CAN BE CARRIED OUT IN BULK AND HAS BEEN REPORTED TO OCCUR WITHOUT RACEMIZATION. THE IODOALANINE USUALLY NEEDS TO BE FRESHLY CRYSTALLIZED BEFORE USE. TREATMENT OF TELLURIUM WITH SUPER HYDRIDE GIVES THE DILITHIODITELLURIDE. THE SOLUTION WAS CHILLED TO -78OC AND THE IODOALANINE WAS ADDED. THE PROTECTED TELLUROCYSTEINE WAS ISOLATED IN 55% YIELD. SCHEME III CLEAVAGE OF THE BENZYL ESTER WITH LIOH FOLLOWED BY IN SITU DEPROTECTION OF THE BOC PROTECTING GROUP WITH TRIFLUOROACETIC ACID WILL GIVE THE AMINO ACID.